Final answer:
The word 'myriad' originally meant 10,000 in ancient Greece but is now used to refer to any large number. Its usage illustrates the evolving nature of language and the Greek's methodical approach to mathematics.
Step-by-step explanation:
The six-letter word that originally meant exactly 10,000 in ancient Greece and today is used to describe any large number is myriad. In ancient Greek times, the term was used in a more precise manner, specifically referring to the number 10,000. Over time, its meaning has evolved to represent any large, indefinite number. This reflects how the understanding and usage of words can transform throughout history.
The concept of myriad also offers insight into the historical significance of mathematical concepts and numeration within ancient civilizations, such as the Greeks who had a systemic approach to mathematics as seen with figures like Pythagoras and Archimedes.